I am a Bertolucci fan, and this film is one of the reasons why. I watch it again and again and never get tired of it. Don't be fooled by the 'losing virginity' theme; this film is about life, and death, and everything that happens in between. It's about what you seek and what you're willing to give up to get it.
One of the best things about this film is that every character has a story, and an arc in the film, most of which is given by just one or two lines or shots in the film. For example, near the end of the film, Sinead Cusack's character slumps at the table after having taken an old friend to the hospital, probably for the last time. She says she misses England "and rain, and milk that goes off", and says that she's tired of looking after people. Then everyone starts coming in and asking about dinner, and she just gets up and opens the fridge. In less than a minute, we see into her life and character in a way that most films would take at least an act to explore. We even learn a lot about Lucy's mother (Lucy is played by a young Liv Tyler), even though she has died before the beginning of the film and never appears in it except in a photograph (also of Tyler).
There is not a flaw in any of the performances. Never do we feel that these are people acting. They just feel like people, interacting, and we always have a feeling of their life leading up to the moments we see them, and they are interesting lives.
The location itself is one of the characters, and it is beautifully shot, the colours saturated and rich. It feels like you can touch the stones, smell the air, feel the grass and flagstones beneath your bare feet. If you don't want to go to Tuscany after seeing this film, you are ill or on the wrong medication. The beauty that is being stolen, or that people want to steal, is not just the beauty of the young virgin on the hill, it is the beauty of life, of living, of learning, of looking back and finally giving it all up, knowing it cannot be stolen. I know that some people criticize Bertolucci for his aesthetic, for bringing the beauty out of every moment, even the horrible ones, and I say to those people that they live the life they choose.
Finally, there is the soundtrack, which runs from alt-pop to classical to everything in between and works perfectly. It illuminates Lucy's internal reality and is true to the music that a girl of her age would have been listening to at that time, and it also helps set the scene and smooth transitions between scenes.
This is a master work by a master director, and one of my favourite films of all time.